1. Field of the Invention
The present invention relates to a recording/reproducing apparatus and a recording/reproducing method, and to an optical disk, all for use in the field of, for example, an optical disk reproducing apparatus.
2. Description of the Related Art
There have been developed optical disk reproducing apparatuses for reproducing an optical disk on which audio data and video data are recorded in a digital form. Such an optical disk reproducing apparatus has widely been utilized as a reproducing apparatus in, for example, motion picture software, karaoke and so on. An optical disk for use in the optical disk reproducing apparatus has the same size as that of a CD (compact disk), and is therefore advantageous in that the whole of the apparatus is miniaturized.
This development of optical disk reproducing apparatuses has been realized under the circumstances that International Standardization of a compression system of videos has been promoted, and an MPEG (Moving Picture Image Coding Expert Group) system and so on have already been standardized.
FIG. 6 is a view illustrating an example of a recording format of audio and video data compression-encoded on an optical disk.
As illustrated in FIG. 6, the recording format comprises a read-in area 1, an information area 2, a data area 3, and a read-out area 4. The information area 2 corresponds to a track (program) 1. The data area 3 on which compressed video data and compressed audio data have been recorded corresponds to the tracks (program) 2 up to 99. Each track (program) of the data area 3 comprises an array of video data V and audio data A physically divided in sectors as illustrated in FIG. 7, and one audio sector A is arranged behind about six continuous video sectors V such that synchronization of the video and audio is established.
The address or the like of a head sector of each track (program) 2 in the data area 3 is recorded in the information area 2. The optical disk reproducing apparatus previously reads the control table in a memory. Upon receipt of the designation of a track (program) to be reproduced, the optical disk reproducing apparatus executes a seek operation by reading a head sector address of the objective track (program) from the control table in the memory.
In the optical disk reproducing apparatus with the structure, although random access on the track (program) unit basis is possible, it is impossible to execute random access on a basis smaller than the track unit, e.g., on the GOP basis, the GOP being an encoding unit of an MPEG video.
In a conventional optical disk reproducing apparatus, random access is not ensured on the basis of a unit smaller than the track. For example, it is impossible to start access in the middle of a track.